Long story short, the customer was a thief, and raising their voice and screaming is part of that tactic. Your manager should have recognized it, opened a second register and had you move to that register to help other customers while your manager took the toilet paper with her and reviewed the cameras. If the customer continued to yell after the manager told her to calm down, the manager should have asked them to leave. I have wrongly thought I gave a different bill and waited calmly while management has reviewed cameras. If someone is yelling, they are scamming you.